This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Background: Many microorganisms produce low-molecular-weight, iron(III)-specific binding compounds called siderophores to compete for iron. Microbes are thought to produce unique siderophore structures to successfully compete for iron against other organisms in their environment. The siderophores isolated from terrestrial bacteria and fungi and from marine bacteria show promise as biomedical agents and for control of microbial growth. The siderophores produced by marine fungi have not been characterized and thus provide an unexplored source of novel bioactive compounds. Hypothesis: Marine-derived fungi produce siderophores with novel structures. Methods: Marine-derived fungal strains are screened for production of siderophores in pure cultures under conditions of iron limitation. Siderophores are isolated and structurally characterized using amino acid analysis, fatty acid analysis, NMR, mass spectrometry, and other techniques, as appropriate. Results and future directions: At this time, we have identified Cunninghamella elegans ATCC 36112 as a siderophore producing marine-derived fungus. A novel siderophore has been isolated from the fungus and characterized using UV-Visible spectrophotometry, electrospray ionization mass spectrometry, and tandem mass spectrometry. We are currently working to purify sufficient material for analysis by NMR, which will allow us to complete the structural determination for this novel siderophore. We have also begun screening several strains of marine-derived yeasts. These strains appear to produce siderophores (based on Fe(III)-CAS assay) and we will begin purification of the compounds immediately. Experiments planned in the immediate future will isolate and structurally characterize siderophores produced by these new strains.